This application claims the priority of PCT application PCT/CH97/00448, filed Nov. 27, 1997, which is incorporated herein by reference.
The invention relates to a method for controlling the introduction depth of an injection needle in accordance with the preamble of claim 1 and to an apparatus for implementing this method as it reads from claim 3.
With conventional injection devices there is often the problem that the operatorxe2x80x94the nurse or the patientxe2x80x94is unable to control, unaided, the introduction depth of the needle. Where a slender child is concerned, in comparison to a corpulent grown-up, a substantially shorter introduction depth suffices. If the injection needle is inserted unnecessarily deep in the tissue skin, pain materializes which is avoidable. In particular, in the case of patients who often have to endure frequent injections, e.g. diabetics, this leads to an aversion to or even a fear of the next injection.
The present invention is thus based on the object of providing a method and an apparatus for controlling the introduction depth of an injection needle by means of which the user is able to set the optimal introduction depth for the nature of the skin tissue concerned.
The invention achieves this desired object by providing a method, comprising the features of the characterizing part of the independent claim 1, and an apparatus, comprising the features of the characterizing part of the independent claim 3.
Due to the shortening of the maximum possible travel H of the injection needle by a spacer, it is possible to vary the introduction depth. This may be done either by a series of spacers differing in axial length x or by a frontal screw-on type spacer. The hollow-cylindrical spacer, arranged concentrically about the injection needle, may be simply snapped or clicked into the needle introduction device used, or be set by frontal screw-mounting to the desired introduction depth.
The needle introduction device is configured either as a separate unit for coupling to a conventional injection device or it may be integrated in the injection device.
When no spacer is clicked into the needle introduction device, or if the frontal screw-mounting spacer is in its resting position, then the maximum possible travel of the injection needle is permitted to thus attain the deepest introduction depth. If a spacer is click-mounted or screw-mounted into the travel of the injection needle, then the maximum travel H is shortened by the amount x and a shorter introduction depth results.
In a preferred embodiment of the invention, the needle introduction device is a separate unit which can be coupled to a conventional injection device, this unit comprising a rear longitudinal part including a piercing needle (which can be coupled to the injection device) and a front longitudinal part including an injection needle for delivery of the fluid into the tissue skin or subcutaneously. Provided between the piercing needle and the injection needle is a flexible connection.
The needle introduction device is connectable via the piercing needle to the pen cartridge of the injection device so that the fluid to be delivered into the tissue skin or subcutaneously is injectable via the injection needle and the procedure of introducing the injection needle into the tissue skin or subcutaneously automatically occurs upon manual activation of a control element of the needle introduction device, accommodated in the rear longitudinal part, and the fluid can be administered via the injection device.
Serving as the control element is an initiator sleeve arranged longitudinally shiftable on a piercing needle mount mounting the piercing needle and cooperates with an injection needle mount, likewise longitudinally shiftable in a stopper sleeve, mounting the injection needle.
Introducing the injection needle into the tissue skin or subcutaneously after manual activation of the initiator sleeve occurs in that the injection needle mount together with the injection needle is automatically moved by means of the force of a spring in the direction of the tissue skin. Following automatic introduction of the injection needle into the tissue skin or subcutaneously, the user is able to administer the dose of fluid required by means of the conventional injection device.
The apparatus in accordance with the invention has the salient advantage that it offers highly reliable assurance in controlling the introduction depth of the injection needle into the tissue skin or subcutaneously.
Further advantageous aspects of the invention read from the dependent claims.